Another idea is get spare set of wheels for dedicated
rain tyres.
After my first season, I realized nothing compares:
rain tyres > 15-20s/lap faster than racing tyres
rain tyres > 10-15s/lap faster than treaded street tyres
Yes, street tyres are faster than race tyres in rain and
rain tyres are fastest of them all! With power-tools, it takes about 5-min to swap wheels.